Background and aims Continuous femoral nerve block (cFNB) has been effectively used after total hip arthroplasty (THA). Recently, transmuscular quadratus lumborum block (tQLB) has been introduced to produce postoperative pain relief after THA. Continuous tQLB (ctQLB) would benefit from the catheter insertion site that is farther away from the surgical site compared with cFNB. No studies have compared analgesic effects of ctQLB and cFNB. In this randomized controlled study, we compared these techniques in patients undergoing THA.

Methods With IRB approval and informed consent, we enrolled 30 patients undergoing unilateral THA, who were randomly divided into two groups receiving either ctQLB or cFNB. Under ultrasound guidance, QLB and FNB were conducted before general anesthesia using 0.25% levobupivacaine 30 ml and 0.5% levobupivacaine 15 ml, respectively, and a catheter was introduced. All patients received continuous infusion of 0.125% levobupivacaine 4 ml/h postoperatively. Postoperative measurements included visual analog scale (VAS), postoperative use of analgesic, cutaneous sensory blockade, motor strength of the thigh, and adverse events for 48 hours.

Results Of the 30 patients, 6 were excluded and 24 (13 and 11 patients in groups QLB and FNB, respectively) were analyzed. VAS on movement at 6 and 24 hours was lower with cFNB than with ctQLB (figure 1). VAS at rest, demands for PCA and other analgesics, and motor strength of the thigh were similar between the two groups. QLB did not produce consistent cutaneous sensory blockade. No severe complication was observed.

Conclusions Analgesic effects of ctQLB were inferior to those of cFNB in patients undergoing THA.